The invention relates to a bearing and bushing assembly for use primarily, but not exclusively in fluid pumping systems.
One of the most serious problems associated with pumps and indeed any rotating equipment that comes into contact with a fluid material, is wear in the bearings and/or bushings associated with such equipment. This wear, in general, is caused by abrasive particles suspended in, or forming part of the material being pumped. The higher the percentage of abrasive particles in the material, the shorter the working life of these components.
While considerable attention has been paid to the design of specific application pumps, little or no thought has been given to substantially overcoming the basic problem of wear, other than to utilize materials in the construction of components that are less subject to wear. With the slow decline in conventional oil reserves, attention is now being directed to the recovery of heavy oil, which heretofore has been uneconomic to recover.
As is well known in the oil and gas industry, heavy oil is difficult to pump, not only because of its viscosity, but also because this oil contains a high percentage of sand, sometimes up to 60%. The result therefore is that wells are shut down and major reserves are left in the ground.
With such an abrasive product, a very specific type of pump is required, and indeed, it is only recently that such a pump has been designed, capable of handling heavy oil. This particular pump, which is classified as a xe2x80x9cTurbo-Discxe2x80x9d pump is the subject of presently pending Canadian Patent Application Serial #2,185,176, filed Sep. 10, 1996, and is currently assigned to CDM Inc, of Calgary, Alberta, Canada.
The apparatus disclosed in the prior design essentially comprises a cylindrical housing having an intake adjacent to one end to recover the viscous oil and sand mixture and a discharge outlet adjacent to its other end through which the fluid can be pumped. An inner impeller rotationally mounted in the housing generates a xe2x80x9cturboxe2x80x9d effect, namely a spiraling, in this case upwardly moving column of fluid which rotates around the housing and thereby induces a flow of the mixture through the intake. A number of rotating discs are arranged in the housing in a separation zone above the intake. These discs are spaced apart from one another and serve to assist in guiding the flow of fluid to the discharge end of the housing. These discs also serve in the separation of the fluid into at least some of its separate components or phases.
Field and bench testing of this pump have shown that its construction does lessen the previously known problem of blade impingement of solids on conventional pumps and hence substantially reduces the blade or disc erosion.
A problem still however exits with regard to components utilized in connecting with this particular pump, in that the bearings and seals, which are subjected to contact with the highly abrasive mixture, are subject to wear.
When this problem becomes evident, the present inventor, whom also invented the xe2x80x9cTurbo-Discxe2x80x9d pump, designed the bushing and bearing assembly which is the subject of the present application.
Accordingly, it is the object of the present invention to substantially reduce the wear in any bearing utilized on contact with abrasive fluids.
It is a further object of the present invention to provide a bearing and bushing assembly that permits abrasive fluid to flow through the assembly in a manner which reduces contact with the metal surfaces.
The present invention therefore comprises a bushing and bearing assembly where the outer surface, a bushing component attached to a rotatable shaft, is provided with a pair of spiral grooves extending the length of the bushing, one groove being in a reverse spiral to the other. The bearing component of the assembly is of composite construction having an outer cylindrical, tubular shell and an inner cylindrical, tubular insert of a material different from that of its outer shell. The surface of the insert which will operationally bear against the grooved surface of the bushing having a parallel, longitudinally extending groove formed therein.